Risk of tsunami underestimated: IAEA

by Kazuaki Nagata

Staff Writer

Japan underestimated the risks of tsunami that led to the nuclear crisis at the Fukushima No. 1 nuclear plant, the International Atomic Energy Agency said in a preliminary summary Wednesday, while pointing out the need to reinforce the independence of its nuclear regulators.

“The tsunami hazard for several sites was underestimated. Nuclear designers and operators should appropriately evaluate and provide protection against the risks of all natural hazards,” reads the IAEA summary.

The IAEA team of experts — which arrived in the country May 23 — visited the Fukushima Nos. 1 and 2 plants, as well as the Tokai No. 2 plant in Ibaraki Prefecture, to investigate the sites in an effort to glean lessons on nuclear safety from the ongoing crisis.

The summary hints that the government needs to review the current nuclear regulatory structure, saying the system “should ensure that regulatory independence and clarity of roles are preserved in all circumstances in line with IAEA Safety Standards.”

Since the March 11 twin disasters that triggered the nuclear accident, calls have been growing for more independence for the Nuclear and Industrial Safety Agency, with some saying it should be divorced from the Economy, Trade and Industry Ministry, which overlooks the utilities industry. At present, NISA is part of METI.

There are also concerns that the roles of NISA and the Nuclear Safety Commission, an independent government panel of experts, remain unclear.

The government “needs to make sure that not only they are independent in structure but also independent in the resources and expertise that they have available,” said Mike Weightman, leader of the IAEA team, after submitting the report to the government at the prime minister’s office.

Weightman said the direct cause of the crisis at the Fukushima No. 1 plant was the tsunami that damaged the cooling system of the reactors.

He also said the government and Tokyo Electric Power Co. were cooperative in disclosing information, which he said contributed to identifying lessons that could be taken from the nuclear crisis.